Prevent panic during wrappedConn close at hammertime (#11219)
* Prevent panic during wrappedConn close at hammertime
Signed-off-by: Andrew Thornton <art27@cantab.net>
* Update modules/graceful/server.go
* Fix extraneous debug in goldmark.go
Signed-off-by: Andrew Thornton <art27@cantab.net>